ORDER IV.—MOTHS AND BUTTERFLIES, 137 
ascertained. Some naturalists think that these feelers servo 
to protect the eyes, but the more rational opinion prevails 
that the antennz, with which all insects are provided, are 
probably the organs of hearing. They are hollow, provided 
with muscles, and placed on each side of the head, like the 
ears of beasts, reptiles, and fishes. 
The use of the proboscis is much better known: it is a 
spiral tongue, formed to coil up like the spring of a watch, 
and it is by means of this organ that the insect is enabled 
to pump out the juice of flowers. This spiral tongue, which 
answers the purpose of a mouth, is placed between the eyes, 
and consists of two lateral halves which are closely united, 
and which form a hollow tube like the proboscis of an ele- 
phant. Its length varies considerably in the different spe- 
cies of butterfly. We find the longest ones in the Hawk- 
moths; but a few species have none at all, as the silk-worms, 
for many live as perfect insects only a few days, and can 
get along without the trouble of procuring food. 
I have often amused myself with experiments upon the 
Hawk-moths and Butterflies which were hatched in a warm 
room as early as the month of March. I have fed them 
with sugar, holding the insect in my fingers by the wings, 
and have seen them seize the piece of sugar with their fore 
feet and, thus holding it, unfold their proboscis, and with its 
saliva moistening the sugar, then sucking the juice, which 
could easily be perceived ascending the trunk. This is an 
experiment which every one can make at pleasure. 
From the most ancient times it has been observed that 
some lepidoptera make their excursions only during the 
night, and conceal themselves during the day ; while others 
are seen flying about only in the daytime, and conceal 
themselves at night. The former are called Nocturnal 
Lepidoptera, as Moths, Millers, Hawk-moths, ete., which 
are recognized by their having antennz without a knob at 
the end, e. g., the Saturnia Io (Figs. 27 and 28). 
